Method and apparatus for locating welds in hollow metal bodies



Dec. 5, 1950 c. E. BOUCHER METHOD AND APPARATUS FOR LOCATING wELDs 1NHoLLow METAL BODIES Filed June 9, 1948 V INVENTOKL (fo/"mack E. Boucher'MJ m /a r n -e y Fini Patented Dec. 5,

UNITED STATES ETENT OFFICE METHOD AND APPARATUS FR LCATING 'WELDS INHOLLOW AMETAL 'BDIES Cormack E. Boucher, Seattle, li/ash.

Application .lune '9, 1948, Serial No. 32,028

(Cl. 25d-65) 9 Claims. 1

The present invention relates to methods and apparatus for locatingirregularities on otherwise smooth surfaces. More specifically theapparatus oi the present invention is particularly adapted for use inlocating welds in the walls of hollow, metal bodies.

In the radiographing of annular welds oi cylindrical bodies such aspipes, it is desirable to pass the source of penetrative rays throughthe interior of the pipe and radicgraph the welded section wrapping afilm around the weld and expose the nlm throughout 360 with a singlePortable X-ray units have been developed together with propulsion meanstherefor whereby welded sections of approximately a mile or so in lengthmay be radiographically inspected while the X-ray unit and itspropelling tractor may be controlled from one end oi thepipe linesection. For exposing the lm about any one welded section, the X-rayunit must be accurately positioned with respect to the weld and, in thecase oi long pipe lines, it is impossible or impracticabie for anoperator to travel through the pipe with the apparatus. Various meanshave been proposed heretofore for guiding the positioning of the sourceof penetrative rays within the pipe line with respect to the weldedsection, but, prior to the present invention, none oi these means hasbeen entirely satisfactory.

It is an'object of the present invention, therefore, to provide a newand improved method and apparatus for locating welded sections inhollow, metal bodies.

In the welding of wall sections of hollow, metal bodies together, theadjacent wall sections are spaced a slight distance apart in order thatthe weld bead will form a homogeneous union between the wall sectionsthroughout their entire thickness. The weld fbead thus inherently formsan irregularity1 on the inner surface o f the body usually in the formof a protuberant ridge, although, under certain circumstances, theirregularity might be in the form of a slight depression. By extensiveobservation, it has been noted that it is virtually impossible to weldtwo adjacent metal wall sections together without forming anirregularity of one sort or another at the juncture. The irregularitythus formed by the welding operation provides an excellent means forpositively locating the welded section and for facilitating thepositioning of the penetrative ray apparatus with respect thereto.

It is a further object of the present invention, therefore, to provide anew and improved means for mechanically feeling the inside of a hollow,

metal body for location of a welded section thereof.

A further object or" the present invention is to provide a new andimproved apparatus for loeating a welded section in a hollow, metal bodyby mechanically exploring the inner surface of the body for theirregularity resulting from the welding operation.

A still iurther object of the present invention is to provide a new andimproved portable AX-ray unit including means for locating weldedsections oi hollow, metal bodies for guiding the positicning of theX-ray unit with respect to such welded sections.

A further object of the present invention i's to provide a new andimproved method for positioning a penetratve ray apparatus within weldedhollow metal bodies for radiographic inspection oi lthe welded area.

For a consideration of what is believed novel and inventive, attentionis directed to the following description talzen in connection with theaccompanying drawing while the features oi novelty will be pointed outwith greater particularity in the appended claims. Y Y

In the drawing, Fig. l is a longitudinal, side elevation illustratingthe weld locating device of the present invention in accordance with oneform thereof; Fig. 2 is a iront end vie-w of the apparatus shown in Fig.1; Fig. 3 is an enlarged, side elevation illustrating certain details ofthe apparatus shown in Fig. l.

Referring now to the drawings, the weld locating device of the presentinvention is illustrated as being mounted upon the housing of a portableX-ray unit lil adapted for movement longitudinally within a hollow,metal body such as a cylindrical pipe line ll. The portable X-ray unitlil is provided with a plurality of supporting wheels la arranged uponthe ends of bracket arms i3, the various supporting kwheels i2 beingspaced about the X-ray unit iii so as to support the unit in apredetermined, longitudinal, axial alignment with the pipe ll. The rearend of the X-ray unit is adaptedto be supported by means of the bracketarm arrangement lil upon the adjacent end of a conduit tractor (notshown), the ends of the arms l!! being provided with a coupling elementl5 extending along the axis of the unit lil. It will be understood bythose skilled in the art that, in the movement of a portable X-ray unitand tractor through a conduit, there will be an inherent tendency forthe apparatus to rotate more or less about the horizontal axisparticularly in negotiating bends in the pipe line. With the arrangementof the supporting wheels l2 and the connection l5 for the conduittractor as shown, the X-ray unit I will be maintained substantially incoaxial alignment with the pipe line Il irrespective of relativerotational movement of the X-ray unit l0 and the conduit tractor aboutthe pipe axis.

Mounted within one end of the housing of the X-ray unit lll is an X-raytube, illustrated at I5, the tube being arranged coaxially with thelongitudinal axis of the housing. The tube is preferably of a typecapable of emitting X radiations throughout an angle of 360 and at leastthat portion of the housing surrounding the X-ray tube i is of amaterial relatively permeable to X radiations. It will be understood bythose skilled in the art that the radiations passing outwardly from thetube spread over a radial area of considerable width, the angle ofspread of radiation in the axial direction being indicated in thedrawing by the angle Il. It is merely necessary, therefore, that theX-ray unit be so positioned with respect to an annular weld indicated ati8 so that the weld will lie within the angle I? of the radiationsemitted by the X-ray tube l5. The dotted lines 25 at the right of Fig. lillustrate the X-ray unit so positioned that the annular weld liessubstantially in the center of the field of radiations emitted by theX-ray tube i3. A nlm holder 2i is shown wrapped around the outside ofthe pipe Il and over the weld IB containing a rllm which may be exposedthroughout the full circumference of the weld at a single energizationof the tube i6.

For locating the weld i8 inside of the pipe and for facilitating thepositioning of the X-ray unit with respect thereto, I provide a detectorresponsive to the surface irregularity created by the Weld bead on theinside of the pipe and which, in this instance, comprises an arm 25pivotally mounted as at 25 upon the housing for the X-ray unit, theouter end of the arm 25 being biased toward the wall of the pipe l! bymeans of a spring 2T arranged between the housing and the crank arm 28formed on the end of the arm 25. The arm 25 extends considerably aheadof the forward end of the X-ray unit l and is provided on its forwardend with a rotatable, slider element 3d. The rotatable, slider element30 is provided with a plurality of ilattened, or concave sides 32 whichsides are adapted to slide against the smooth, inner surface of the pipell. At least the leading edge portions of the sides 32 of the sliderelement 3E! are sharpened in a direction transversely to the line ofmovement. In the modication shown, the corners of the slider element 3i)are dened by hardened, steel inserts 3l and which are sharpened bysliding the various peripheral sides of the Wheel across an abrasivestone with the inserts 3l at opposite corners of the wheel sidesimultaneously bearing against the stone surface. In 'this manner, sharpedges are formed on each of the tip portions. So long as the sliderelement S5 is moved along a smooth, wall surface, it will not rotate onthe end of the arm; but, immediately upon engagement of the sharpleading edge 3l of the slider element with an irregularity in thesurface of the pipe, the slider will resist continued forward movementand Will rock through an angle of ninety degrees about the cornerportion which will be held relatively stationary by the surfaceirregularity of the weld.

Any suitable means may be provided for actuation by the relativemovement of the slider element 30 upon the end of the arm 25; but, asshown in the drawings, I provide an electrical switch 35 mounted on thebracket 36 pivotally supporting the slider element 30 upon the end ofthe arm 25. Fixedly secured to the shaft of and rotatable with theslider element 30 is a squared member 37 and which is engaged by aroller 3B mounted upon the end of a spring nger 39 secured at itsopposite end onto the body of the switch 35. Upon rotation of the sliderelement 3U, the spring finger 39 will be actuated so as, in turn, toactuate the contacts of the switch 35. The contacts of the switch 35 maybe connected by a conductor 48 extending back along the arm 25 and totheterminals ll on the X-ray unit housing. The signal can be carriedrearwardly of the pipe line to the control station through the cable 42.Following the instant of the signal, the operator will allow tractor topush the X-ray unit farther ahead by a predetermined amount,corresponding to the distance between the element 3l] and the center ofthe tube field. The tractor will then be stopped, the tube energized andthe iilm exposed, following which the unit l| can be shifted to the nextweld.

Attention is directed to the fact that the pivotal supporting means forthe arm 25 is arranged to the rear of the effective eld of theradiations from the tube i6 while the rotatable slider element 3o andswitch 35 extend considerably ahead of the eld of radiations. It will beunderstood that, if the detector for weld locating unit comprising theslider element 50 and the switch 35 were mounted in the radial plane ofthe tube Hi, the mass of such parts would cause an undesirable shadowupon the nlm.

In order that the arm 25 supporting the detector will not cast a shadowupon the iilm and thus, possibly, obscure certain portions thereof, itis preferred that the arm 25 be made of a material relatively permeableto X radiation, for example, aluminum or magnesium. For the same reason,the conductors 25 extending from the switch 35 should also be made of asimilar material. It will be obvious that the arm 25 may be mountedotherwise than as shown upon the X- ray unit, or even upon thepropulsion tractor, if desired.

Having described the invention in what is considered to be simplifie-d,preferred embodiments thereof, it is desired that it be understood thatthe specific details shown are merely illustrative and that theinvention may be carried out by other means.

I claim:

1. An apparatus for locating a Weld in a hollow, metal body, saidapparatus comprising a support adapted for movement inside said body, amember mounted on said support and adapted for rubbing along the innersurface of said body, said member including a portion normally inactivein passing over smooth surface portions of said body but active to causeactuation of said member upon engagement thereof with an irregularity onthe inner surface of said body, and means operatively associated withsaid member for providing an indication upon actuation o said member.

2. An apparatus for radiographing a weld in a hollow, metal body, saidapparatus comprising a support adapted for movement inside said body, asource of penetrative rays mounted on said support, an arm pivotallymounted on said support, means biasing said arm toward the wall of saidbody, a slider element movably mounted on the end of said arm forengaging against the surface of said body, said slider element includinga sharp edged portion, said sharp edged portion being adapted to slidefreely along a smooth surface but to offer resistance to further forwardmovement upon contact with any surface irregularity of said body, andindicator means operatively associated with said element for providingan indication upon engagement of said element with a surfaceirregularity.

3. An apparatus for radiographing an annular weld in a hollow, metalbody, said apparatus comprising a support, a source of penetrative raysmounted on said support and adapted to be carried thereby along theinside of said body, ar arm mounted on said support, one end of said armextending toward a side wall of said body, a slider element mounted onthe end of said arm and adapted to slide along the surface of said body,a forward edge of said slider element being sharpened in the directiontransverse to the line of movement of said support and adapted forresisting the movement of said slider element upon engagement with asurface irregularity of said body, and an indicator means operativelyassociated with said Slider element and adapted to bf actuated therebyupon engagement of said edge with a surface irregularity on said body.

4. An apparatus for radiographing an annular weld of a hollow,cylindrical, metal pipe, said apparatus comprising a housing, aplurality of wheels mounted on said housing in a spaced apart relationthereabout for supporting said housing in a predetermined, alignedrelation with the axis of said pipe, an X-ray tube mounted in fr;

said housing capable of emitting radiations throughout an angle of 360,an arm pivotall mounted on said housing, spring means biasing one end ofsaid arm toward the side Wall of said pipe, a slider element mounted onthe end ci' f said arm and adapted to slide along the surface of saidpipe, the leading edge portion of said slider element being sharpenedtransversely to the line of movement whereby upon engagement with anirregularity on the surface of said pipe A continued forward movement ofsaid slider ele.- ment will be resisted, an indicator means mounted onsaid arm and adapted for actuation by said slider element upon contactwith a surface ir regularity.

5. An apparatus for radiographing an annular weld in a cylindrical,metal pipe, said apparatus comprising a housing, a plurality of Wheelssecured to said housing for engaging with the inner surface of said pipeat spaced apart points z around said housing for supporting said housingin a predetermined aligned relation with respect to the longitudinalaxis of the pipe, a source of penetrative rays mounted within saidhousing capable of emitting penetrative radiations f throughout an angleof 360 about the axis of said pipe, an arm pivotally mounted on saidhousing, spring means biasing one end of said arm toward the side Wallof said pipe, a rotatable slider element mounted on the end of said arm,said element having a plurality of fiattened sides, the leading edges ofsaid flattened sides being sharpened whereby upon engagement of saidsharpened edges with an irregularity on the surface of said pipe, saidslider element will Eil be caused to rotate upon said arm, a switchmounted on said arm cooperatively adjacent said slider element andadapted to be actuated thereby so as to provide an indication for thelocation of the weld.

6. The method of radiographing a weld in a hollow body which comprisespositioning a nlm over said weld on the outside of said body, passing asupporting means for a source of penetrative rays into said body,feeling the inner surface of said body with a feeler on said meansresponsive to engagement thereof with the roughened area formed by saidweld, positioning said source adjacent said area and exposing said lmwith said source.

7. The method of radiographing a weld in a hollow body which comprisespositioning a lm over said weld on the outside of said body, passing asupporting means carrying a source of penetrative rays through said bodyand spaced a predetermined distance from said body, feeling the innersurface of said body with a feeler on said means responsive toengagement thereof with rough surface portions for locating theroughened area of the weld a predetermined distance ahead of said sourceand then moving said source ahead said predetermined distance andexposing said lm with said source.

8. The method of radiographing a weld in a hollow body, which comprisespositioning a film over said weld on the outside of said body, insertinga source of penetrative rays into said body, feeling the inner surfaceof said body for the roughened area thereof formed by the weld bead witha feeler responsive to engagement thereof with a rough surface portion,moving said source into a position beneath said area and exposing saidfilm with said source.

9. The method of radiographing a weld in a hollow body which comprisespositioning a nlm over said weld on the outside of said body, moving asource of penetrative rays inside said body, feeiing the inner surfaceof said body with a feeler responsive to engagement thereof with a roughsurface portion a predetermined distance ahead of said source forlocating the roughened area thereof formed by said weld, and after Saidarea is located moving said source ahead by an amount equal to saidpredetermined distance and then exposing said film with said source ofrays.

CORMACK E. BOUCHE-R.

REFERENCES CITED The following references are of record in the iile ofthis patent:

UNITED STATES PATENTS Number Name Date 1,662,429 Lowy Mar. 13, 19282,091,522 Perry Aug. 13, 1937 2,201,311 Halliburton May 21, 19402,397,887 Haynes Jan. 12, 1943 2,313,310 Arnold Mar.r 9, 1943 2,339,274Kothny Jan. 18, 1944 2,340,923 Boucher Feb. 8, 1944 2,350,832 SegesmanJune 6, 1944 2,371,658 Stewart Mar. 20, 1945 2,412,174 Rhoades Dec. 3,1946 2,436,047 Martin Feb. 17, 1948 2,470,743 Hochgesang May 17, 1949

